Method for treating osteoarthritis

ABSTRACT

A method and composition for treating osteoarthritis with ion-channel regulators is disclosed. The ion-channel regulators are used alone or in combination with other osteoarthritis treatment agents, including but not limited to injectable agents such as viscosupplements and steroids. A composition comprising one or more ion-channel regulator(s) and one or more osteoarthritis treatment agent(s) is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the treatment of pain and inflammationin body tissues. In particular, the present invention relates to methodsand compositions for treating osteoarthritis using ion-channelregulators.

2. Discussion of the Background

Osteoarthritis is a degenerative joint disease in which cartilage andbone are primarily affected. Osteoarthritis is especially common amongolder people, and usually affects a joint on one side of the body. Inosteoarthritis, the cartilage breaks down and wears away, causing pain,swelling, and loss of motion of the joint. Further details are providedin Osteoarthritis, National Institute of Arthritis and Musculoskeletaland Skin Diseases, National Institutes of Health, NIH Publication No.02-4617, July, 2002 which is incorporated herein by reference.

Rheumatoid arthritis is a systemic disease which, when manifested injoints, primarily affects the synovial membrane. Rheumatoid arthritisbegins at a younger age than osteoarthritis, is usually presentbilaterally in the joints, and sometimes results in feelings ofsickness, tiredness, and fever. Further details are provided inRheumatoid Arthritis, National Institute of Arthritis andMusculoskeletal and Skin Diseases, National Institutes of Health, NIHPublication No. 04-4179, May, 2004 which is incorporated herein byreference.

Inflammation is a fundamental biological process consisting of a dynamiccomplex of cytologic and chemical reactions that occur in the affectedblood vessels and adjacent tissues in response to an injury or abnormalstimulation caused by a physical, chemical, or biological agent. Theprocess of inflammation includes: 1) local tissue reactions andresulting morphologic changes; 2) destruction or removal of injuriousmaterial; and 3) responses that lead to repair and healing. Theso-called “cardinal signs” of inflammation are redness, heat (orwarmth), swelling, pain and inhibited or lost function. All of thesesigns may be observed in certain instances, but no one of them isnecessarily always present. A disease that involves inflammation isherein referred to as an “inflammatory disease”.

The proteins known as cytokines are important factors in the onset andmaintenance of inflammation. Cytokines, which are produced by synoviallining cells, cartilage cells, as well as by other types of cells,regulate numerous biological responses, including cell growth, and thenature and extent of proteins that are made by cells. Cytokines includeinterferons (IFNs), colony stimulating factors (CSFs), interleukins(ILs), and tumor necrosis factors (TNFs). It is known that the presenceof inflammatory cytokines (IL-1, IL-8, TNF) initiates a series ofcomplex cellular and molecular events, including the expression ofadhesion molecules, the production of secondary inflammatory mediators(prostaglandins, leukotrienes), and the production of growth factors.

Arthritis is an inflammatory disease characterized by inflammation of ajoint, which term includes synovial tissue and membranes. There are manyforms of arthritis, including without limitation, osteoarthritis(hypertrophic or degenerative arthritis), rheumatoid arthritis,arthritis due to infection (tuberculosis, Lyme disease, rheumatic fever,etc.), suppurative arthritis, juvenile arthritis, and gouty arthritis.Elevated tissue levels of IL-1, IL-8, and TNF are found in arthritis andin other inflammatory conditions.

In osteoarthritis, the cartilage that covers the ends of the bones thatform the joint is slowly degraded by the action of various enzymes,particularly the matrix metalloproteinases (MMPs) which are secretedinto the synovial fluid of the joint by the synovial lining cells inresponse to stimulation by various proinflammatory cytokines,particularly IL-1 and TNF. The destruction of cartilage by the MMPsperpetuates the inflammatory reaction and leads to the joint painassociated with osteoarthritis. Further details are provided in“Biochemistry and Metabolism of Articular Cartilage in Osteoarthritis”,H. J. Mankin and K. D. Brant, in Osteoarthritis: Diagnosis andMedical/Surgical Management, 2^(nd) Ed., R. W. Moskowitz, D. S. Howell,V. M. Goldberg, and H. J. Mankin, W. B. Saunders Co., Philadelphia(1992), which is incorporated herein by reference.

Ion channels are glycoprotein structures located in the membrane ofcells, including synovial cells and cartilage cells, which allow ions,particularly monovalent and divalent cations and anions, to pass throughthe membrane. Ion channels include but are not limited to calcium-ionchannels, sodium-ion channels, potassium-ion channels, chloride-ionchannels, cation-ion channels, anion-ion channels, connexon channels andnon-selective ion channels.

Ion-channel regulators are a known group of agents, usually chemical innature, that alter the entry of certain ions into or out of cells andcellular organelles, depending on whether the intracellular orextracellular concentration of the particular ion is greater, and on theelectrical potential difference that exists between the inside and theoutside of the cell. The combined effect of the concentration differenceand the electrical potential difference is called the electrochemicalgradient. When the gate of an ion channel is open, the ions will flowdown their electrochemical gradient unless they are prevented from doingso as, for example, by means of a chemical ion-channel regulator.Ion-channel regulators that cause a reduction in the ion flow that wouldotherwise occur are referred to as “ion-channel blockers.” Ion-channelregulators that cause an increase in the ion flow that would otherwiseoccur are referred to as “ion-channel activators.”

Ion-channel regulators are commonly used for treating a variety ofconditions, including cardiac conditions such as atrial fibrillation,supraventricular tachycardias, hypertrophic cardiomyopathy andhypertension, as well as migraine headaches, the prevention of braindamage, and other disorders. Certain ion-channel regulators and relatedcompounds have been described in the art as being useful in thetreatment of inflammatory diseases. For example, Thorpe et al. (U.S.Pat. No.6,416,758) disclose antibody conjugate kits for selectivelyinhibiting VEGF binding to only one (VEGFR2) of the two VEGF receptors.The antibodies inhibit angiogenesis and induce tumor regression, and canbe used for treatment of all conditions where angiogenesis is a factor(including arthritis). Thorpe, et al. mention CAI, an angiogenesisinhibitor that acts as a calcium-channel regulator that prevents actinreorganization, endothelial cell migration and spreading on collagen IV.

Stamler, et al. (U.S. Pat. No. 6,359,182) disclose C nitroso compoundsderived from a wide variety of drugs, including known calcium channelregulators (verapamil, diltiazem, etc.). These derivatives providerelaxation and platelet inhibiting effects, and due to their NO donorfinction, are said to be useful for treating arthritis.

Schonharting, et al. (U.S. Pat. No. 6,337,325) provide a combinationpreparation which includes a compound having a phosphodiesteraseinhibiting action, and a compound which reduces the biologicallyeffective intracellular Ca2+ content (such as verapamil). Theirpreparation can be used to treat rheumatoid arthritis.

Medford, et al. (U.S. Pat. No. 5,811,449) disclose a method fortreatment of atherosclerosis and other cardiovascular and inflammatorydiseases that are mediated by VCAM 1 (“vascular cell adhesion molecule1”). The list of diseases includes rheumatoid arthritis andosteoarthritis. The dithiocarboxylates and other compounds used with themethod can be attached to a large number of pharmaceutically-activecompounds, including calcium-channel regulators (verapamil, diltiazem,nifedipine).

Certain known compositions for the relief of pain associated withinflammatory disease states may contain ion-channel regulators andrelated compounds. For example, Breault (U.S. Pat. Nos. 6,365,603 and6,100,258) describes aromatic/phenyl compounds useful for inhibiting thepain enhancing effects of E-type prostaglandins. The compounds can beused to treat pain associated with rheumatoid arthritis, osteoarthritis,and osteoporosis, and may contain additional agents such ascalcium-channel regulators.

Mak (U.S. Pat. No.6,190,691) provides methods for treating severalinflammatory conditions that are mediated by TNF production (includingrheumatoid arthritis). Treatment is accomplished by administering atherapeutically effective amount of any of a number of compounds,including calcium-channel regulators such as verapamil, nicardipine orisradipine. Mak teaches direct injection of large amounts of(+)-verapamil (20-40 mg in a 10 mg/mL solution) into joints for thetreatment of rheumatoid arthritis.

There is no known cure for osteoarthritis, and consequently clinicalefforts aimed at treating it are presently directed toward symptomaticrelief of pain. Conventional therapies include treatment with analgesicsor non-steroidal anti-inflammatory drugs (aspirin, ibuprofen, naproxen,COX 2 inhibitors such as CELEBREX and VIOXX, and the like),interarticular injection of corticosteroids and unmodified or modifiedhyaluronan (a treatment called viscosupplementation), as well as the useof steroids, antibiotics, glucosamine, chondroitin, immunomodulators,and penicillamine. Traditional remedies such as the application of heatfor temporary, local pain relief are helpful for some patients, andsuitable exercise and physical therapy programs can help in maintainingjoint mobility. Joint replacement surgery may be advised in severecases.

Despite the availability of a wide range of medications and treatmentmodalities for arthritis and inflammatory diseases in general, asdescribed above, none has proved to be entirely satisfactory forosteoarthritis. In particular, there remains a need for innovativetreatments that target the underlying cause of osteoarthritis, forexample the production of MMPs, and thereby help reduce, eliminate, orslow its progression (expressed symptomatically by bone erosion,cartilage erosion, inflammation, swelling, abnormal neovascularization,etc.).

BRIEF SUMMARY OF THE INVENTION

According to its major aspects and broadly stated, the present inventionprovides a method and compositions for treating the pain, inflammationand loss of function associated with osteoarthritis, by using certainagents that are capable of regulating the movement of ions in and out ofcells through structures embedded in the cell membrane called ionchannels. As briefly described above, such agents are referred to hereinas “ion-channel regulators”.

One embodiment of the present invention comprises a method for treatingosteoarthritis, which comprises directly administering to the affectedjoint, preferably by direct injection into the closed cavity of thejoint (“intraarticular injection”), a therapeutically effective amountof at least one ion-channel regulator, alone or in combination with atleast one other osteoarthritis treatment agent.

The method of the present invention treats the underlying cellularprocesses. that lead directly to the pain and tissue destructionassociated with osteoarthritis. In one embodiment, the inventioncomprises administering to the synovial tissue an effective amount ofion-channel regulator; i.e., an amount that is sufficient to reduce anyor all of the symptoms of osteoarthritis without producing any of theundesirable side effects resulting from an overdose of ion-channelregulator, such as tissue death or injury, joint swelling, etc. Thepresent invention provides a means for interfering with cell signalingby the cytokine IL-1, the major inflammatory cytokine associated withosteoarthritis, thereby leading to lower MMP levels and correspondinglylower cartilage destruction and resultant pain. It is believed that thismethod does not necessarily affect the production of IL-1, but ratheralters its consequences by interfering with the synthesis of MMPs at apoint subsequent to the binding of IL-1 to its receptor on the surfaceof the cells, which is known to those skilled in the art as being thefirst step in the synthesis process. This method is contrasted with theuse of certain ion-channel regulators as a means of interfering with theproduction of the cytokine TNF, e.g. in the treatment of the systemicinflammatory disease rheumatoid arthritis (see Mak, supra).

Ion-channel regulators contemplated as being useful in the presentinvention include, but are not limited to, calcium-channel regulators,sodium-channel regulators, potassium-channel regulators,chloride-channel regulators, cation-ion channel regulators, anion-ionchannel regulators, non-selective ion channel regulators andconnexon-channel regulators (i.e., chemical agents that regulate themovement of ions and molecules through connexons in synovial cells,which consist of the protein known as connexin 43).

A preferred method of administering the ion-channel regulator is todirectly inject a pharmaceutically acceptable composition containing atleast one ion-channel regulator into the closed cavity of an arthriticjoint. The ion-channel regulator may be administered alone or incombination with other medicaments, preferably other chemical agentsused to treat osteoarthritis (herein referred to as “osteoarthritistreatment agents”). Osteoarthritis treatment agents include, but are notlimited to pharmaceutically acceptable viscosupplements, steroidal andnon-steroidal anti-inflammatory agents, glucosamines, chondroitins, andso forth.

In another embodiment, the present invention comprises a novelcomposition useful for treating osteoarthritis in accordance with thepresent invention. The composition of the invention comprises at leastone ion-channel regulator and at least one other osteoarthritistreatment agent. In one preferred embodiment, a composition comprises atleast one ion-channel regulator and at least one injectableosteoarthritis treatment agent, most preferably a viscosupplement. Thecompositions of the invention may also contain other materials such asfillers, stabilizers, coatings, colorizing and flavoring agents,preservatives, fragrances, and other additives known in the art.

In its various embodiments, the present invention provides severaltreatment modalities to users. Treatment may consist of theadministration of an effective amount of at least one ion-channelregulator, preferably in a pharmaceutically acceptable composition thatcontains at least one such compound. Alternatively, treatment mayinclude administration of at least one ion-channel regulator incombination with administration of at least one other osteoarthritistreatment agent, preferably in a composition containing both theion-channel regulator and the other osteoarthritis treatment agent. Thetreatment can readily be customized to the individual patient's needs,and may be used instead of or in conjunction with other treatmentmodalities including, but not limited to, physical therapy, treatmentsthat provide localized pain relief (heat, massage, application ofliniments, etc.), and other medications that help reduce disability,relieve pain, and improve the patient's quality of life.

Other features and advantages of the present invention will be apparentto those skilled in the art from a careful reading of the DetailedDescription of the Invention presented below.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides methods and compositions whereinion-channel regulators are used to treat the inflammation, pain andtissue destruction associated with osteoarthritis.

Without intending to be bound by theory, it is believed that thepresence of inflammatory cytokines in the joint leads to the entry andexit of certain cellular ions, e.g. calcium, sodium, potassium, chlorideions, etc., into and out of cells in the joint, particularly synoviallining cells, resulting in initiation of what is called cell signalingor cell transduction. The terms are herein used interchangeably. As thesignaling process develops, other events occur, including the activationof protein kinase C, changes in intercellular communications, andalteration of protein expression by the cells. If these processes arenot regulated properly they eventually lead to osteoarthritis, which ischaracterized by symptoms that include pain, inflammation, abnormalneovascularization, bone and cartilage erosion, loss of function, and,ultimately, degeneration of the affected joint.

Entry of certain ions, particularly calcium and sodium ions, has beenfound to be critically important to the ability of the cells to secreteMMPs. As previously described, MMPs are believed to be primarilyresponsible for the destruction of joint cartilage that leads to jointpain associated with osteoarthritis. It is generally believed that themost important factor responsible for secretion of MMPs is interleukin-1(IL-1). See, “Biochemistry and Metabolism of Articular Cartilage inOsteoarthritis”, H. J. Mankin and K. D. Brant, supra, which isincorporated herein by reference.

The specific MMPs whose levels in joint fluid are regulated by IL-1, andwhose dysregulation mediates the development of osteoarthritis, includeMMP-1, also known as collagenase-1; MMP-2, also known as gelatinase A;MMP-3, also known as stromelysin-1; MMP-8, also known as collagenase-2;and MMP-13, also known as collagenase-3. The levels of MMP activityproduced by synovial tissue from patients having osteoarthritis isgreater than the corresponding level obtained from patients who do nothave arthritis (see “Increased Intercellular Communication through GapJunctions May Contribute to Progression of Osteoarthritis”, A. A.Marino, D. D. Waddell, O. V. Kolomytkin, W. D. Meek., R. Wolf, K. K.Sadasivan, and J. A. Albright; Clinical Orthopaedics & Related Research422:224-232 (2004), which is incorporated herein by reference.

Ion-channel regulators, particularly calcium-channel regulators such asverapamil and nifedipine, have been found to be capable of interferingwith the effect of IL-I on synovial cells (see “Interleukin 1β SwitchesElectrophysiological States of Synovial Fibroblasts”; O. V. Kolomytkin,A. A. Marino, K. K. Sadasivan, R. E. Wolf, and J. A. Albright, AmericanJournal of Physiology, 273 (Regulatory Integrative Comp. Physiol.42):R1822-R1828 (1997), which is incorporated herein by reference. It isbelieved, without being bound by theory, that the mechanism responsiblefor the beneficial effects of treating osteoarthritis with ion-channelregulators in accordance with the present invention involves theirability to antagonize the proinflammatory effect of IL-1, which ifunchecked, leads to elevated levels of MMPs (which, in turn, leads tothe chronic inflammation, cartilage destruction, pain and loss of jointmobility associated with osteoarthritis).

The ability to regulate or block the signaling pathway at the level oftransmembrane ion current (including, but not limited to, transmembranecalcium ion current) via administration of ion-channel regulators isbelieved to have clinical benefits. For example, by affecting the entryof calcium ions into the affected synovial cells, the calcium signalingpathway is disrupted, preventing the intracellular events that culminatein inflammation and cartilage destruction.

As previously mentioned, ion-channel regulators may sometimes bereferred to in the art as ion-channel blockers or ion-channelactivators, depending on their effect on ion flow. Although these termsmay refer to the same chemical agents, the terminology “ion-channelregulators” is believed to be more accurate in the context of thepresent invention. Ions passing through channels can turn on processes(manufacturing MMPs, for example), but these processes are always normalprocesses in the sense that the reason the ion channels evolved in thefirst place was to facilitate the process. The pathology relates to thelevel of regulation; that is, osteoarthritis develops when aninappropriate amount of ions pass through a channel. So, it may be saidthat the present invention treats osteoarthritis by blocking thesechannels, which amounts to allowing fewer ions to pass through themembrane, so that the situation is closer to normal. However, the coinhas another side. It is not always the case that few ions equal normaland many ions equal abnormal; sometimes, many ions equal normal, and fewions equal abnormal. In this case, the present invention would not treatosteoarthritis by “blocking” the ion channel, but by “stimulating” it.Hence, the term “ion-channel regulator” is intended to include chemicalagents that perform both functions.

Ion-channel regulators are commonly used for treating a variety ofcardiac conditions, including atrial fibrillation, supraventriculartachycardias, hypertrophic cardiomyopathy and hypertension, as well asmigraine headaches, the prevention of brain damage, and other disorders.These chemical agents are well-known to those skilled in the medicalarts and it is contemplated that all known and future discoveredion-channel regulators will be useful in the present invention.

Specific examples of ion-channel regulators include, but are not limitedto, calcium-channel regulators, sodium-channel regulators,potassium-channel regulators, chloride-channel regulators,cation-channel regulators, anion-channel regulators, connexon-channelregulators and non-selective ion-channel regulators, as well as specificantibodies against the channels. As the name implies, calcium-, sodium-,potassium-, chloride-, cation- and anion-channel regulators respectivelyregulate the movement of calcium ions, sodium ions, potassium ions,chloride ions, anions and cations through ion channels in the membranesof cells. Non-selective ion channels are ion channels that allow anycombination of anions and cations to pass through the membranes ofcells, and non-selective ion-channel regulators regulate the movement ofthose ions. Connexon-channel regulators regulate the movement of ionsthrough connexons. Connexons are a class of ion channels consisting ofthe protein connexin 43, known to be present in synovial tissue and tooccur in increased amounts in arthritic joints. It is believed that alltypes of ions with a molecular mass less than 300 are able to passthrough connexons. The amino acid sequence of connexin 43 is listed atthe Universal Protein Resource, where it is identified as P17302. A“specific antibody against the channel” means an antibody against anantigenic determinant of the ion-channel protein that is capable ofblocking the function of the ion channel when the antibody binds to theantigenic determinant.

Representative examples of calcium-channel regulators includeamlodipine, bepridil, diltiazem hypochloride, felodipine, gallopamil,isradipine, nicardipine, nifedipine, nimodipine, nitrendipine,verapamil, and mixtures thereof, as well as specific antibodies againstthe channels. Representative examples of sodium channel regulatorsinclude quinidine, encainide, mexitil, disopyramide, procainamide,tetrodotoxin, and mixtures thereof, as well as specific antibodiesagainst the channels. Representative examples of potassium channelregulators include tedisamil, glibenclamide, dofetilide, amiodarone,azimilide, tolbutamide, propranolol, and mixtures thereof, as well asspecific antibodies against the channels. Representative examples ofchloride channel regulators include5-Nitro-2-(3-phenylpropylamino)benzoic acid, chlorotoxin, picrotoxin,and 9-Anthracenecarboxylic acid and mixtures thereof, as well asspecific antibodies against the channels. A very extensive listing ofcalcium- and sodium-channel regulators that may be suitable for thepresent invention is found in previously-cited Mak, U.S. Pat. No.6,190,691, which is incorporated herein by reference.

Representative examples of connexon-channel regulators include lindane,octanol, 18α-glycyrrhetinic acid, calcium-ion concentration, pH, mimeticpeptides, and certain antibodies. It is known that certain mimeticpeptides can be used to block connexons and therefore may be suitable asconnexon channel regulators in accordance with the present invention.For example, the synthetic tridecapeptide VCYDKSFPISHVR (residue numbers63-75), and the undecapeptide SRPTEKTIFII (residue numbers 204-214) areable to block connexin 43, as described in Leybaert, L., Braet, K.,Vandamme, W., Cabooter, L., Martin, P. E. M. and Evans, W. H., “Connexinchannels, connexin mimetic peptides and ATP release”. Cell Commun.Adhesion. 10:251-257, 2003. Mimetic peptides consisting of 2 or moreamino acids can similarly be formed employing any portion of the aminoacid sequence of connexin 43, and the peptides will be effective, somemore than others, in regulating the movement of ions through theconnexon. Peptides that consist of amino acids located in thetransmembrane or extracellular domains of connexin 43 will beparticularly effective connexon channel regulators.

It is also anticipated that the connexon can be regulated by antibodiesdirected against the transmembrane or extracellular domains of theconnexon. In this case, the synthetic peptides may be injected intoanimals for the purpose of eliciting an immune response consisting ofantibodies against epitopes located on the peptides. Suitable proceduresfor obtaining and purifying the antibodies are described in Harlow, E.and Lane, D., “Antibodies: A Laboratory Manual.” Woodbury, N.Y.: ColdSpring Harbor Laboratory Press, 1988.

In one embodiment of the present invention, a method for treatingosteoarthritis comprises directly administering to the joint aneffective amount of at least one ion-channel regulator. Administeringthe ion-channel regulator is preferably accomplished by direct(intraarticular) injection of a composition comprising at least oneion-channel regulator into an arthritic joint. Intraarticular injectiondiffers from other methods of administering ion-channel regulators inthat it allows biologically sufficient concentrations of ion-channelregulator to be applied to the affected synovial tissue without the riskof producing the undesirable side-effects that can occur as the resultof the higher concentrations of ion-channel regulator required by otheradministration techniques. Injection techniques are known to thoseskilled in the art. For example, a useful description for injecting theknee joint is given in “Viscosupplementation Under FluoroscopicControl,” D. Waddell, D. Estey, D. C. Bricker, and A. Marsala, AmericanJournal of Medicine in Sports, 4:237-241 and 249, 2001, which isincorporated by reference herein.

In one embodiment of the invention, an effective amount of one or moreion-channel regulators is administered to an osteoarthritic joint in apharmaceutically acceptable composition. An “effective amount” is anamount that is sufficient to reduce any or all of the symptoms ofosteoarthritis in the treated joint, such as inflammation, pain,stiffness and/or loss of finction, without producing any of theundesirable side effects resulting from an overdose of ion-channelregulator, such as tissue death or injury, joint swelling, etc. What isan effective amount will vary depending on the ion channel, the methodused for administration and the joint being treated. In someembodiments, a combination of ion-channel regulators, e.g. acalcium-channel regulator and a sodium-channel regulator, may beeffective.

An effective amount of ion-channel regulator for treating osteoarthritisin accordance with the present invention using intraarticular injectionmay be in the range of 0.00001-2.0 mg, preferably dissolved or suspendedin physiological saline or other vehicle appropriate for injection intothe body. Preferred compositions comprise one or more ion-channelregulators at a total concentration of 0.00001-2.0 mg/mL. Typically 1-4mL of the composition may be injected into the joint at one time.Administration of a total dose of more than 2.0 mg of ion-channelregulator to a joint by intraarticular injection has been found on thebasis of appropriate studies of synovial tissue to be likely to produceundesirable side effects resulting from the toxic effect of theion-channel regulator on joint tissue at that level. An effective amountof ion-channel regulator used in the present invention is an order ofmagnitude less than the amount of (+)-verapamil that is taught in theprior art as being effective for the treatment of rheumatoid arthritisby intraarticular injection. See, for example, Mak U.S. Pat. No.6,190,691, col. 83, lines 35-54. As one specific example of the presentinvention, an effective amount of verapamil may be 0.02-0.5 mg whendirectly injected into an adult knee joint.

In another embodiment of the invention, one or more ion-channelregulators may be administered in combination with one or more otherosteoarthritis treatment agents, either in separate compositions or inthe same composition. Preferably, the other osteoarthritis treatmentagent is in the form of an injectable composition, i.e. a compositionthat is suitable for being injected directly into the affected joint(intraarticular injection). The treatment method of the presentinvention can readily be customized to the individual patient's needs,and may be used instead of or in conjunction with other treatmentmodalities including but not limited to physical therapy, treatmentsthat provide localized pain relief (heat, massage, application ofliniments, etc.), and with other medications that help reducedisability, relieve pain, and improve the patient's quality of life.

Accordingly, examples of treatments contemplated by the presentinvention include an intraarticular injection of a composition includingone or more ion-channel regulators followed by another intraarticularinjection of another osteoarthritis treatment agent, e.g. aviscosupplement, steroid or other injectable osteoarthritis treatmentagent; an intraarticular injection of an ion-channel regulatorcomposition followed by oral or intravenous administration of anotherosteoarthritis treatment agent such as a non-steroidal anti-inflammatorydrug; an intraarticular injection of a single composition comprising atleast one ion-channel regulator and at least one viscosupplement,steroid or other injectable osteoarthritis treatment agent; and soforth.

A treatment composition according to one embodiment of the inventioncomprises one or more ion-channel regulator(s) and one or more otherosteoarthritis treatment agent(s). The individual concentrations of theion-channel regulator(s) and the other osteoarthritis treatment agent(s)are sufficient to provide an effective amount of each ingredient to theaffected joint. Preferably, the composition comprises ion-channelregulator(s) at a concentration of 0.00001-2.0 mg/mL and otherosteoarthritis treatment agent(s) at a concentration of 0.01-25mg/mL.

In one embodiment, the composition is suitable for intraarticularinjection in accordance with the method of the present invention, andboth the ion-channel regulator and other osteoarthritis treatment agentare “injectable”. As used herein, the term “injectable” means anyosteoarthritis treatment agent that is in a form suitable forintraarticular injection. In one embodiment, the injectable otherosteoarthritis treatment agents may comprise at lease one corticosteroidsuch as a glucocorticoid. As one specific non-limiting example, thecomposition of the present invention may comprise 1-25 mg/mL of theinjectable steroid osteoarthritis treatment agent methylprednisoloneacetate.

In another embodiment, the injectable other osteoarthritis treatmentagent may comprise at least one viscosupplement. As used herein and inthe art, the term “viscosupplement” refers to any substance that is usedto restore and/or increase the cushioning and lubrication of arthriticsynovial fluid by intraarticular injection. Preferred viscosupplementsinclude hylan, hyaluronic acid and other hyaluronan (sodium hyaluronate)compounds, which are natural complex sugars of the glycosaminoglycanfamily. Hyaluronan, in particular, is a long-chain polymer containingrepeating disaccharide units of Na-glucoronate-N-acetylglucosamine. Byway of example, commercially available hyaluronan viscosupplementsinclude Synvisc®, Hyalgan®, Supartz®, and Orthovisc®. As one specificnon-limiting example, the composition of the present invention maycomprise 1-15 mg/mL of a hyaluronon compound.

Other osteoarthritis treatment agents comprising the composition of thepresent invention may also include those used in any modality ofarthritis treatment, such as oral administration, intravenousadministration, etc. Examples of other osteoarthritis treatment agentsinclude, without limitation, non-steroidal anti-inflammatory drugs(NSAIDS) such as ibuprofen, naproxen, and COX-2 inhibitors; analgesicssuch as aspirin and acetaminophen; glycans, including glucosamines, e.g.glucosamine sulfate and glucosamine hydrochloride; and proteoglycans,such as chondroitin compounds, as well as various other known narcotics,steroids, antibiotics, immunomodulators, penicillamine, and the like.

The compositions of the present invention may also contain othermaterials such as fillers, stabilizers, coatings, coloring agents,preservatives, fragrances, and other additives known in the art. Thecompositions may be in liquid or gel form and may be provided intime-release formulations.

The present invention may be illustrated by the following non-limitingexamples:

EXAMPLE 1

Patient M. L. is a 57-year-old female with osteoarthritis of the kneejoint (grade IV on the Kellgren-Lawrence scale). An assessment of painand function of the joint was made immediately prior to treatment, andat various times after treatment, using the visual analog scale (VAS)for pain, and the Western Ontario and McMaster Universities (WOMAC)osteoarthritis index, which assesses pain, function and stiffness inarthritic joints. A more detailed description of the nature and use ofthese clinical endpoints is given in “Clinical Development Programs forDrugs, Devices, and Biological Products Intended for the Treatment ofOsteoarthritis, U.S. Dept. of Health and Human Services, Food and DrugAdministration, July 1999”, which is incorporated by reference herein.

Immediately after the initial VAS and WOMAC measurements were made, thepatient's right knee was injected with 1 mL of saline containing 0.2 mgof the calcium-channel regulator verapamil using the following basicinjection procedure:

The patient is seated in a standard dental chair, with the knee flexedbetween 30-40 degrees. The knee is prepared with a sterile prep ofbetadine. Ethyl chloride spray provides skin anesthesia for theinjection of 1% plain Xylocaine, which is injected into the skin andsubcutaneous tissue. Precaution is taken not to inject any fluid intothe knee. The patient is cautioned that although the majority of painwill be obviated, there will be some pain as the needle passes throughthe synovial lining. After enough time has elapsed to achieve effectivelocal anesthesia, it is often useful to activate a fluoroscopy unit inthe lateral position to obtain a view of the patella and contact zone ofthe femoral condyle with the tibial plateau. The point of insertion forthe 21-gauge injection needle is then chosen utilizing the lateral viewof the knee and referencing the point of a standard anterolateralarthroscopy portal. The injection site is proximal to the normal portalsite by some 1 to 1½ centimeters. Using this as a guide, the needle isadvanced inwardly to the intraarticular space just at the anteriorcontact point of the femoral condyle and the tibial plateau. At thispoint, free injection of verapamil is allowed without injecting the softtissues. The above procedure is described in more detail in theaforementioned journal entitled “Viscosupplementation Under FluoroscopicControl,” cited supra.

Table 1 below summarizes the VAS and WOMAC scores obtained before and atseveral time points after the injection. TABLE 1 Arthritis Scores ofPatient M.L. Physician Patient Time VAS VAS WOMAC Prior to injection 7267 57  1 week after injection 44 43 47  2 weeks after injection 20 2538.5  3 weeks after injection 20 33 46  8 weeks after injection 20 33 3412 weeks after injection 20 28 41 16 weeks after injection 28 34 33 20weeks after injection 15 27 37

As shown in Table 1, immediately before treatment, the patient had aphysician VAS score of 72, a patient VAS score of 67, and a WOMAC scoreof 57. One week after injection, the patient's pain had decreasedmarkedly, as indicated by the reduced VAS scores of 44 and 43, and thepatient's overall finction had improved, as evidenced by the decrease inWOMAC score to 47. The patient was followed periodically for up to 20weeks following the injection, and it was found that the reduction inpain and improvement in function continued to be observed.

EXAMPLE 2

Patient O. B. is a 73-year-old male who suffered from osteoarthritis inthe left knee (grade IV on the Kellgren-Lawrence scale). As can be seenin Table 2 below, prior to treatment, the patient had a physician VASscore of 50, a patient VAS score of 46 and a WOMAC score of 30. Afterthe patient's left knee was injected with 1 mL of saline containing 0.2mg of verapamil using the same basic procedure described in Example 1,both VAS scores and the patient's WOMAC score improved significantly.Table 2 below summarizes those results: TABLE 2 Arthritis Scores ofPatient O.B. Physician Patient Time VAS VAS WOMAC Prior to injection 5046 30 1 week after injection 12 28 12 2 weeks after injection 11 25 10 3weeks after injection 10 10 6 8 weeks after injection 12 17 4

EXAMPLE 3

Patient R. R. is a 41-year-old male suffering from osteoarthritis in theleft knee joint (grade H on the Kellgren-Lawrence scale). Prior totreatment, the patient's chief complaint was pain, as evidenced by apatient VAS of 55. Following treatment with 0.5 mg of verapamil in 1 mLof saline employing the same basic injection procedure as set forth inExample 1, the patient's pain decreased and remained low throughout theperiod for which data was collected. Table 3 below summarizes thoseresults: TABLE 3 Arthritis Scores of Patient R.R. Physician Patient TimeVAS VAS WOMAC Prior to injection 35 55 17  1 week after injection 10 128  2 weeks after injection 6 26 7  3 weeks after injection 10 16 6  8weeks after injection 11 20 6 12 weeks after injection 12 20 6 16 weeksafter injection 10 10 6

EXAMPLE 4

Patient A. W. is a 56-year-old female who initially had physician andpatient VAS scores of 50 and 59, respectively and also had limited jointfinction as indicated by a WOMAC of 43. Following treatment with 0.2 mgof verapamil in 1 mL of saline employing the same basic injectionprocedure as set forth in Example 1, her clinical condition improvedmarkedly, as shown in Table 4. TABLE 4 Arthritis Scores of Patient A.W.Physician Patient Time VAS VAS WOMAC Prior to injection 50 59 43 1 weekafter injection 0 5 12 2 weeks after injection 7 3 7 3 weeks afterinjection 8 6 13 8 weeks after injection 2 2 15

The destructive action of MMPs and the role of potentially useful agentsto block this destructive activity can be studied in a model systeminvolving synovial tissue obtained from knee joints, a pro-inflammatoryagent which causes the tissue to secrete MMPs, and an agent whoseeffectiveness in reducing MMP production is to be assessed. A proceduresuitable for performing this assay is described in Kolomytkin, O. V.,Marino, A. A., Waddell, D. D., Mathis, J. M., Wolf, R. E., Sadasivan, K.K. & Albright, J. A., “IL-1β-induced production of metalloproteinases bysynovial cells depends on gap-junction conductance during the earlystage of signal transduction.” Am. J. Physiol: Cell Physiol.282:C1254-C1260, 2002. which is incorporated by reference herein andshould be consulted for more detail.

The following results of tests using the above-described procedureconfirm that the administration of an ion-channel regulator to synovialtissue in accordance with the present invention significantly reducesthe production and secretion of MMPs by the treated synovial tissue. Aspreviously stated, this reduction in MMPs is believed to lead to thereduction in pain and improvement in function achieved by the method ofthe present invention, e.g. as demonstrated in Examples 1-4 above.

EXAMPLE 5

When approximately 20 mg of synovial tissue was obtained from a78-year-old female with osteoarthritis (grade IV, Kellgren-Lawrencescale), it was found using the above-described procedure that the amountof MMPs produced under standard incubation conditions was reduced 60%when the calcium-channel regulator verapamil was applied at aconcentration of 0.005 mg/mL, total volume, 1 mL; and the MMPs werereduced 63% when the concentration of verapamil was increased to 0.05mg/mL in the same volume. In another patient, a 61-year-old female, theMMP activity was decreased by 63% in the presence of a verapamilconcentration of 0.005mg/mL and by 77% in the presence of verapamil at aconcentration of 0.05mg/mL; both with total volume of 1 mL. Similarresults were found using synovial tissue from a 69-year-old male and a70-year-old female, both of whom had osteoarthritis (grade IV,Kellgren-Lawrence scale).

EXAMPLE 6

Experiments were performed using the procedure described above, butusing the calcium-channel regulator nifedipine instead of verapamil. Itwas found that the amount of MMPs produced under standard conditions byapproximately 20 mg of synovial tissue obtained from a 73-year-oldfemale with osteoarthritis (Grade IV, Kellgren-Lawrence) was reduced by69% in the presence of a 0.015 mg/mL of nifedipine, total volume, 1 mL;and the MMP activity was reduced by 76% at a nifedipine concentration of0.03 mg/mL, total volume, 1 mL. When the assay was repeated usingsynovial tissue from a 59-year-old female with osteoarthritis (grade IV,Kellgren-Lawrence scale), the MMP activity produced by the tissue understandard conditions was reduced by 64% and 71% when the tissue wasexposed to 0.015 mg/mL nifedipine and 0.03 mg/mL nifedipine,respectively. Similar results were obtained using the synovial tissue ofa 50-year-old male and a 68-year-old female, both of whom hadosteoarthritis (grade IV, Kellgren-Lawrence scale).

EXAMPLE 7

Experiments were performed using the procedure described above, butusing the sodium-channel regulator procainamide instead of acalcium-channel regulator. It was found that the amount of MMP producedunder standard conditions by approximately 20 mg of synovial tissueobtained from a 77-year-old male with osteoarthritis (Grade IV,Kellgren-Lawrence) was reduced by 67% when the tissue was treated with0.01 mg/mL; total volume, 1 mL.

EXAMPLE 8

Experiments were performed using the procedures described above, butusing the sodium-channel regulator tetrodotoxin. It was found that theamount of MMP produced under standard conditions by approximately 20 mgof synovial tissue obtained from a 64-year-old male with osteoarthritis(Grade TV, Kellgren-Lawrence) was reduced by 100% when the tissue wastreated with 0.00002 mg/mL; total volume, 1 ML.

The trypan blue exclusion test is commonly used to evaluate whethercells are alive or dead. The test consists of adding an appropriateamount of trypan blue dye to the environment of the cells. Cells areable to exclude the dye if they are healthy, but if they are injured ordead, the dye enters the cell and stains it blue. By means of the trypanblue exclusion test, as described in Example 9 below, it was found thation-channel regulators produce harmful and lethal effects on cells whenused to treat osteoarthritis at concentrations taught by the prior artto treat rheumatoid arthritis.

EXAMPLE 9

Approximately 20 mg of synovial tissue from a human knee joint wasexposed to 10 mg/mL of the ion-channel regulator verapamil (1 mL totalvolume) and assessed using the trypan blue dye exclusion test. It wasfound that the synovial lining cells in the tissue were killed. Somecell death occurred after exposure for several hours, and all of thecells in the tissue were killed following exposure for 12-16 hours.Similar tests were performed on additional samples of human synovialtissue using various concentrations of different ion-channel regulators.

By means of the above-described tests, it was discovered that theconcentration of verapamil, nifedipine, procainamide, and otherion-channel regulators used in compositions of the present inventionmust be no greater than 2.0 mg/mL, and that the total dose of theion-channel blocker must be no greater than 2.0 mg. The markedly lowerconcentration and dosage used in the practice of the present inventionhave the further significant advantage of completely avoiding systemicside-effects which may be anticipated to occur at the concentrations anddoses described in the prior art, e.g. intraarticular injection of 20-40mg of verapamil in a 10 mg/mL aqueous solution as described in Mak U.S.Pat. No. 6,190,691 for treatment of rheumatoid arthritis.

The foregoing description is considered as illustrative only of theprinciples of the invention. Further, since numerous modifications andchanges will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact details shown and describedherein, and accordingly, all suitable modifications and equivalents maybe resorted to, falling within the scope of the invention. Thus, it willbe apparent to those skilled in the art that many changes andsubstitutions can be made to the preferred embodiments herein describedwithout departing from the spirit and scope of the present invention asdefined by the appended claims.

1. A method for treating osteoarthritis which comprises injecting aneffective amount of one or more ion-channel regulators into the closedcavity of a joint having osteoarthritis.
 2. A method as described inclaim 1 wherein the effective amount is 0.00001-2.0 mg of ion-channelregulator(s) delivered in 1-4 mL of a pharmaceutically acceptablecomposition.
 3. A method as described in claim 1 wherein the ion-channelregulator(s) is selected from the group consisting of calcium-channelregulators, sodium-channel regulators, potassium-channel regulators,chloride-channel regulators, anion-channel regulators, cation-channelregulators, non-selective ion channel regulators, connexon-channelregulators, combinations of the foregoing and antibodies against therespective channels.
 4. A method as described in claim 1 which furthercomprises administering an effective amount of one or more otherosteoarthritis treatment agent(s) in combination with the ion-channelregulator(s).
 5. A method as described in claim 4 wherein the otherosteoarthritis treatment agent is administered separately from theion-channel regulator(s).
 6. A method as described in claim 4 whereinthe ion-channel regulator(s) and injectable osteoarthritis treatmentagent(s) are injected together as a single composition.
 7. A method asdescribed in claim 6 wherein the composition comprises 0.00001-2.0 mg ofion-channel regulator(s) and 0.01-25 mg/mL of injectable osteoarthritistreatment agent(s).
 8. A method as described in claim 4 wherein theother arthritis treatment agent(s) is selected from the group consistingof viscosupplements, corticosteroids, steroidal and non-steroidalanti-inflammatory drugs, analgesics, glucosamines and other glycans,chondroitin and other proteoglycans, narcotics, steroids, antibiotics,immunomodulators, and penicillamine.
 9. A method as described in claim 1wherein a composition comprising a 0.00001-2.0 mg/mL of a calciumion-channel regulator and/or a sodium ion-channel regulator is injectedinto a knee joint.
 10. A method as described in claim 9 wherein theion-channel regulator(s) is selected from the group consisting ofverapamil, nifedipine, procainamide, tetrodotoxin and combinationsthereof.